DesignLights Consortium Releases Second Draft of Update to Technical Requirements for Horticultural Lighting

March 1, 2021
Comments on Version 2.1 are due by April 9; DLC plans to make changes effective July 1.

MEDFORD, MA – March 1, 2021 – The DesignLights Consortium (DLC) today released the second draft of updated Technical Requirements for Horticultural Lighting (Version 2.1). Scheduled to take effect on July 1, the proposed changes would establish Qualified Products List (QPL) eligibility for three additional product types. Comments on the proposal are due by April 9.

First unveiled in October, the DLC’s Horticultural Lighting Technical Requirements V2.1 would add DC-powered fixtures, externally supplied actively cooled horticultural fixtures, and LED replacement lamps to the DLC’s Horticultural Lighting Program. The DLC is proposing changes to specifications related to all three product types in response to stakeholder comments received last fall. 

“The DLC is committed to ensuring that our specifications related to this fast-growing lighting sector keep pace with evolving technology, while meeting the needs of commercial cultivators and promoting greater energy efficiency,” DLC Executive Director and CEO Christina Halfpenny said. “These changes will support eligibility on our QPL for fixtures that enable greater whole facility energy savings by removing excess heat from the grow environment, while adding eligibility and performance criteria for LED replacements that will facilitate growers’ transition from legacy lighting to highly efficient, horticultural fixtures.”

The proposed V2.1 policy defines externally supplied actively cooled horticultural fixtures as those in which liquid, often water or a water/glycol solution, flows through input and output ports of each fixture in the system, channeled through a cooling plate or other heat exchanger within the fixture. In adding these products to its Horticultural Lighting Program, the DLC provides descriptions of how to test and report on them to ensure performance comparable to products listed under previous versions of the policy. Changes related to these fixtures in response to comments the DLC received following release of the first draft of V2.1 last fall, include removal of requirements specific to the cooling system and not measurable at the fixture level, and the following new proposals:

  • New self-protect functionality requirements;
  • Revisions to requirements for testing and reporting with respect to fixture-level allowable operating conditions for cooling systems;
  • Reporting of image showing photosynthetic photon efficacy (PPE) as a function of inlet fluid temperature.

V2.1 would also allow two new types of LED horticultural lighting equipment to be listed on the QPL: DC-powered fixtures and LED replacements for linear fluorescent lamps and for mogul-base high intensity discharge (HID) lamps. For DC-powered fixtures, the newest version of the policy differs from the earlier draft by removing the proposed requirement for maximum cabling length testing, and by proposing:

  • Revisions to testing and reporting of range of loading points required for the test power source report;
  • Reporting of cabling conditions to maintain less than two percent cabling loss for a fully loaded power source.

For LED replacement lamps changes from Draft 1 in response to stakeholder comments include clarification of eligibility information, revision of electronics lifetime requirements, and proposals for:

  • Reporting intended mounting of screw-base replacements for HID lamps;
  • Allowing directional screw-base replacements for HID lamps;
  • Reporting beam and/or field angle for all lamps.

The DLC’s Horticultural QPL currently contains more than 280 products, with more being reviewed and added regularly.  An increasing number of electric utilities rely on the DLC horticultural lighting specification and QPL in the design of energy efficiency programs for commercial cultivators. About a dozen North American utilities now require the use of QPL products as a prerequisite for EE incentives; many others have incorporated the DLC Technical Requirements into their programs while not yet requiring use of products on the QPL. Two states with cannabis-specific energy efficiency regulations offer a compliance pathway that requires use of the DLC’s Horticultural Lighting QPL. To assist licensees in these states, the DLC’s Horticultural Lighting QPL offers a search filter to find products compliant with these regulations.

The DLC will accept comments on draft Technical Requirements for Horticultural Lighting V2.1 through Friday, April 9 via a comment form (download from: emailed to [email protected].  Full details of the draft policy will be provided during an informational webinar on Thursday, March 11 from 1-2pm EST (

About DesignLights Consortium: The DesignLights Consortium® (DLC) is a non-profit organization whose mission is to achieve energy optimization by enabling controllability with a focus on quality, people, and the environment. The DLC promotes high-quality, energy-efficient lighting products in collaboration with utilities and energy efficiency program members, manufacturers, lighting designers, and federal, state, and local entities. Through these partnerships, the DLC establishes product quality specifications, facilitates thought leadership, and provides information, education, tools and technical expertise.


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